Recently, mobile phones and tablet PCs embedded with super small-sized compact camera modules are being developed. A conventional digital camera module mounted on the mobile phones has suffered from disadvantages in that a gap between an image sensor converting an outside light to a digital image or a digital video and a lens cannot be adjusted. However, a lens driving device such as a VCM (Voice Coil Motor) configured to adjust a gap between an image sensor and a lens has been recently developed to enable a camera module to obtain a further improved digital image and a digital video.
In general, a VCM mounted on a camera module is configured such that a mover mounted with a lens therein moves upward from a base to adjust a gap between the lens and an image sensor arranged at a rear surface of the base. The conventional VCM is configured such that an elastic member presses the mover to contact the base in a case no driving signal is applied. That is, the conventional VCM is configured such that, under a state where the elastic member presses the mover, an electromagnetic force for driving the mover must be greater than elasticity of the elastic member and self-weight of the mover in order to allow the mover to be distanced from the base.
Furthermore, the mover of the conventional VCM has a displacement of approximately 30 μm to 50 μm depending on posture of the VCM. Thus, the mover in the conventional VCM suffers from disadvantages in that it has a displacement depending on the posture of the VCM, includes a non-moving section where the mover is not driven even if a driving signal is applied, and the mover is driven by an auto focus algorithm not reflected therewith to thereby take too much time for auto focusing.